Two piece cans are conventionally used to package beverages, such as beer and carbonated soft drinks. Such cans are often made from aluminum and are formed by attaching a circular lid to a generally cylindrical can body formed by a drawing and ironing process. Typically, the diameter of the open end of the can body is reduced prior to attaching the lid in order to enable reducing the diameter of the lid. The reduction in the diameter of the can end is accomplished in a series of operations referred to as "necking".
In order to avoid wrinkling or otherwise undesirably distorting the can end, necking is performed in a number of incremental steps, with the diameter of the open end being reduced only slightly in each step. FIG. 1 shows the open end 3 of a can body 2 as it undergoes successive necking operations. Although, for simplicity, only three discrete necking operations are shown in FIG. 1, it should be appreciated that a larger number necking operations will frequently be utilized. A variety of methods have been employed to perform the necking operation. In one approach, referred to as die necking and disclosed in U.S. Pat. No. 5,755,130 (Tung et al.); U.S. Pat. No. 4,519,232 (Traczyk et al.) and U.S. Pat. NO. 4,774,839 (Caleffi et al.), each of which is hereby incorporated by reference in its entirety, the open end of the can body is forced into a die having an inwardly tapered surface that permanently deforms the metal inward. Another approach, referred to as "spin necking," involves reducing the can end diameter by pressing the can end against a rotating tool.
A variety of machines have been developed for necking can ends. One such machine 6, which employs a die necking process, is shown in FIGS. 2-5. Such machines are available from Belvac Production Machinery of Lynchburg, Va., as model 595 6N/8. As shown best in FIGS. 1 and 2, such machines typically comprise a plurality of modules, designated 11, 17, 19, and 21, attached to a unitary base 5. An input chute 8 directs the can bodies 2 to an input module 11--specifically, to one of the pockets of a multi-pocket input feed wheel 10 that forms a portion of the input module. The input feed wheel 10 is constructed similar to the intermediate wheels 18, discussed below, except that its pockets have a saw tooth geometry that aids in picking cans from the input chute 8. The input feed wheel 10 carries the can body counterclockwise, when viewed from the front, approximately 210.degree. and deposits it into a first necking module 17--specifically, into one of the pockets of a multi-pocket rotary necking station 16 that forms a portion of the necking module.
Using techniques well known in the art, in the necking station 16, the open end of the can body 2 is brought into contact with a die so as to reduce its diameter slightly, as previously discussed. The rotary necking station 16 carries the partially necked can body clockwise and deposits it into a first intermediate module 19--specifically to one of the pockets of a multi-pocket intermediate wheel 18 that forms a portion of the intermediate module. As discussed further below, the intermediate wheel 18 carries the can body counterclockwise and deposits it into one of the pockets of the next multi-pocket rotary necking station 16, which further reduces the diameter of the can end. Thus, a intermediate wheel 18 is disposed between each pair of necking stations 16 and carries the can body from the each necking station to the next down stream necking station. The necking process is repeated in each necking station 16 of the machine 2 so as to gradually reduce the diameter of the can end 3. As many as nine necking stations 16 may be incorporated into a single machine 2.
As shown in FIG. 3, each intermediate module 19 comprises a base plate 64 that supports a bearing housing 60 and rear support plate 62 that, in turn, support the drive shaft 32 for the intermediate module. The drive shaft 32 is driven by a gear 24, affixed to its rear end, as discussed further below. The shaft 32 has a hub 90 at its front end that supports the intermediate wheel 18. As previously discussed, the intermediate wheel 18 has a plurality of pockets 56 formed on its rim 94. Circumferentially extending front and rear stationary plates 92 and 93, respectively, project outward from the hub 90 and extend to just below the rotating rim 94 so as to form an annular passage 95. A pair of baffles (not shown) divide the annular passage into upper and lower halves 95' and 95", respectively.
Piping 88 conveys suction 99 from a vacuum source 84 to a valve 86. A manifold 87 directs the suction from the valve 86 to the lower portion 95" of the annular passage via openings 97 in the lower half of plate 93. From the lower portion 95" of the annular passage, the suction 99 is directed to each of the pockets 56 in the lower half of the wheel 18 via the vacuum ports 58. The upper portion 95' of the annular passage is vented to atmosphere via an opening 96 in the upper half of plate 93. Thus, suction 99 is applied to the pockets 56 as they rotate counterclockwise past the lower portion 95" of the annular passage and is released as they rotate past the upper portion 95' of the annular passage--that is, suction is applied to each of the pockets 56 from about the 3 o'clock location, at which time the they receive a can body 2 from the upstream necking module 17, to about the 9 o'clock location, at which time they discharge the can body to the downstream necking module.
A set of upper and lower guide plates 66 and 70, respectively, are located in front of the intermediate wheel 18. In addition, another set of upper and lower guide plates 68 and 72 are located behind the transfer wheel. The guide plates are supported from a bracket 78 by spacers 74, 76, 80 and 82. The guide plates ensure that the can bodies maintain their position along the flow path formed by the intermediate module 18.
Returning to FIG. 2, the last necking module 16 deposits the can body 2 to a discharge module 21--specifically to one of the pockets in a discharge wheel 20 that forms a portion of the discharge module. The discharge wheel 20, which is constructed similar to the intermediate wheels 18, carries the can body counterclockwise and deposits it into a discharge chute 22. Although the can body 2 is carried circumferentionally by the wheels 10, 18 and 20 and necking stations 16, the general flow path of the can body through the machine is along a linear, horizontally oriented path from left to right as viewed in FIG. 2.
The input feed module 10 and the discharge module 21 each employ a suction system for retaining and releasing can bodies of the type describe above with reference to the intermediate module 19.
As shown in FIGS. 4 and 5, the input feed wheel 10, intermediate wheels 18, and discharge wheel 20 are each driven by a shaft 31 that is, in turn, driven by a gear 24. The necking stations 16 are also driven by a shaft 34 driven by a gear 24. The gears 24 are indexed and meshed so that the pockets of one component are in registration with the pockets of the adjacent components. One of the gears 24' is driven through a gear box 26 by a motor 28 using a belt drive 30. The gear 24' then drives the two immediately adjacent gears 24, which, in turn, drive the next gears, and so on. Thus, the gear train for the necking machine comprises a row of gears each of which engages the adjacent gear. As shown in FIGS. 4 and 5, the gear 24' that is driven directly the gear box is part of the intermediate module 19' is located in the center of the machine.
In order to fully neck the can body 2, it is generally necessary to perform more than the eight or nine necking operations available in conventional necking machines of the type shown in FIGS. 2-5. In the past, additional necking operations were performed by connecting two necking machines via a conveyor 40, as shown in FIG. 6, so that the second machine was downstream of the first machine and received partially necked can bodies from the first machine. The second machine then performed further necking operations on the can end.
Unfortunately, use of the conveyor 40 to couple the necking machines 6 has several drawbacks, including damage to the cans during conveyance and jamming of the cans in the conveyor, which requires a stoppage of the machines. Also, since the conveyor mixes the can from each necker, all of the components must be checked when a problem is detected in a can from one of the neckers.
Consequently, it would be desirable to provide a method and apparatus for reliably transferring can bodies between two machines that perform operations sequentially on can bodies.